JP-B2-4234235 and JP-A-2002-281774 describe a thermo-magnetic engine using temperature characteristics of a magnetic substance. In the engine, a magnetic field is applied to a cylindrical body so as to define a high-temperature part and a low-temperature part front and behind the cylindrical body in a rotation direction so that the cylindrical body is rotated.
However, when the cylindrical body is rotated, the high-temperature part and the low-temperature part move, so that thermal efficiency of the engine is low.